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<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      line {
        stroke: #000;
        stroke-width: 5px;
      }
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  <body>
    <svg width="300" height="180">
      <!-- 两点决定线段 -->
      <line x1="0" y1="0" x2="200" y2="0"></line>
    </svg>

    <svg width="300" height="180">
      <!-- 折线 -->
      <polyline points="3,3 30,28 3,53" fill="none" stroke="black"></polyline>
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    <svg width="300" height="180">
      <!-- 矩形 -->
      <rect x="0" y="0" height="200" width="300" style="stroke: #000; fill: red"></rect>
    </svg>
  </body>
</html>
